Electric switch



' Spt. 1,1925.

BURNHAM ELECTRIC SWITCH Fil ed Feb; 17, 1921 2 shun-shun. 12

Patented Sept. 1, 1925.

UNITED STATES PATENT OFFICE.

enonen A. BURNHANE, OF sauces, massacnusnrrs, AssmNomBY MESNE ASSIGN- MEN'IS, '10 coNnIrnLncTmcAL MANUFACTURING COMPANY, 1 CORPORATION or MASSACHUSETTS.

tionary switch members and a movable brush-member, it is found that currents of relatively high valuetend to force the brush laminae outwardly away from contact with the stationary switch members and thereby reduce the contact pressure and consequent ly the current-carrying capacity of the switch. Due to the alternating magnetic effect, the brush laminae tend to vibrate and arcing may occur which will burn the contact faces and reduce the current-carrying capacity. l

An object" of this invention is to provide anelectric switch with movable and stationary contact members" so arranged that they will not tend to separate when carrying currents of high value, and may even tend to press morefirmly together, thereby to increase the contact pressure and the current-carrying capacity of the switch.

In carrying out this objectof the invention, I may provide the stationary switch members with brush members so arranged that the toes or contact faces thereof are directed inwardly toward each other; and I may employ some form of movable switch member other than a brush member for the bridging member. \Vith this arrangement, the magnetic effect of the current tends to move the brush laminae in the same direction as before, or outwardly, but due to the relatively reversed angle 'of the toes of the brush members, the laminae are now caused to press with greater force against the cooperating contactmember, and consequently the current-carrying capacity of the switch is not reduced and may even be enhanced by the magnetic effect of currents of high values.

The current-carrying capacity of an electric switch is limited by the rise in temperature of the conducting components re- ELECTRIC SWITCH.

-App1ication filed February 17,1921. Serial No. 445,757.

sulting from thecurrent carried by them. A considerable amount of heat is developed at the junction of the stationary and movable switch-members, due to the contact resistance. The heat is conducted into the stationary switch members and brush member and is finally dissipated, but the contact junction, and the brush member in particular, will be relatively highly heated in comparison with other conducting components of the switch.

A further object of this invention is to provide an electric switch having means to dissipate the heat generated at the contact junction and thereby lower the temperature rise of the contact-members and increase the current-carrying capacity of the switch.

In carrying out this object of the invention, I may employ a brush-member as one contact-member and a co-operating contact-member having a slotted or grooved contact face arranged to provide a plurality of conducting bars with intermediate oil passages. Due to this arrangement the bars act to dissipate rapidly the heat generated at the contact junction, and by reason of its good mechanical contact with the brush-member, when the switch is closed, said bars serve to abstract and dissipate heat from the brush-member. Furthermore, oil has access directly to the contact face of the brush member and will cool it.

The current-interrupting capacity of an electric switch has some dependence upon the speed at which the circuit is interrupted and, other things being equal, that switch having the greater speed of movement of the movable switch member to open position will have the greater current-interrupting capacity. The solid bar or brush member .which has heretofore comprised the bridging member'of the movable switch .vention' may have its bridging-member- 'fformed wth a plurality of oil passages thcrethroug'h arranged in the direction of movement of the said bridging-member whereby to present reduced surface to be acted upon by the oil. and "facilitate the speed or movement of the switcl'ianember. The bridging member may be constructed of a plurality of bars placed on edge with oil spaces tlierebetween and adapted to engage the stationary switch-member in edgewise order. The bridging-member thus arranged serves to abstract heat from the contact junction and in addition to being kept cool by provision of the oil passages, serves to keep the stationary contact members cool.

it. further object is to provide the novel featuresabove set forth as an attachment to certain existing forms of switches.

A. further object is generally to improve the construction and operation of anelec-- tric switch.

Fig. 1 is a side elevation in section of an oil immersed electric switch embodying my invention.

Figft?) is a sectional view, along lines of 22 of Fig. 3, of the bridging member.

Fig. 3 is a plan view of the bridging member of F 2.

Fig. l is a detail of the stationary brushmembers and bridging-members in the open position of the switch.

5 is a section oil the bridging-member along" line 55 of Fig.

6 is asectional detail of a stationary brush-member.

Fig. 7 is an'end viewol the brush-member .of Fig. 6.

8 is perspective view of the brushniember holder.

is a detail of a modified form of statlonary contac member and removable brushanember.

Fig. 10 is .an end View of the stationary contact member of Fig.

Fig. 11 is a detail of the end of a. modified form of stationary contact-member.

Fig. 12 is a sectional detail of the contact. member of Fig. 11. As here shown my invention is embodied in the switch including the frame 10 from which the oil receptacle 11 is removably dependent. Stationary switch-members are carried by said frame and include the inbars 15 are formedof a plurality of lai'ninze assembled to form the shank-portions 5" and toe downwardly retlexed end portions 1 or toes 15 terminating in the contact faces 15. d hile the brush-members may be secured to the contact blocks 11- or, if desired directly to the studs 18 of the stationary switch-members, in any suitable manner l find that unless care is exercised in design of the securing means, certain. laminae of against which the ends of the laminae olthe brush-member abut.

A brazing metal, or solder, is run into the interstices between the brush-member and holder so that both are mechanically and electrically connected. The side portions 16 of the holder serve to conduct current from the side-edges and the shoulder 16 from the end edges of each lamina of the brusli-meinbers so that each lamina carries mainly but its just proportion of the total current carried by the switch and consequently no portion of the shank of the brush-member is likely to become independently excessively heated;

holder is formed with the ears 16 having screw openings through which screws 17 are passed and removably threaded into said blocks 1d by which said brush members are secured to said blocks.

fir stationary auxiliary contact-member is carried by each brush-member. Said contaet-men'iber is of U-sha-pe and has the contact face 18 and the ears l8 which straddle the brush-holder and through WlHCl'l screws 19 passed to secure it removably to the brush holder.

Said brushanembers are removably secured to the lower faces of said blocks 14; and thearrangement is such the brush-members and the movable"switchanembers hereinafter to be described may be applied to eriisting switell-structures, if desired, by securing the stationary brush-members to the stationary contact members and substituting the new bridging member l'or the removable brush-member.

lhe stationary brush-members are applied to the switch-studs so that their toes 133 are inwardly directed toward each other and the contact faces are in the same plane for engagement with the movable switch-member.

The movable switch-member includes the *arr anged te provide increased cooling effect insulating rod 20' to thel'ower end of whieh which latter they are removably secured.

the movable contact or bridging member @Spa'cing washers 27 are disposed on said carried. A rod 21 is secured to the upper end of said rod 20 and extends through an opening in the switch frame and is connected with switch operating mechanism 22, which latter is or may be of more or less usual con struction.

- A movable contact or bridging member of thegc'ontact. faces of the movable and stationary switch-members, and thereby in creased curfint-carrying capacity; and increased SpeedQof opening; and thereby increasedgcurrent-interrupting capacity of the switchi' s' an object of this invengion.

The diovable contact or bridgi g-member is herein shown as formed of a plurality of relatively thin and wide bars arranged on edge in a supporting member and spaced apart to provide oil passages 23 therebetween. This structure is illustrated more particularly in Fig. 3. The top edges of said bars are'adapted to engage the contact faces of the stationary brush-members. Inasmuch as the bars are relatively thin and are surrounded by oil, heat generated at the junction of said bars and brush-member is rapidly dissipated so that the temperature rise at the junction is kept down to a low value.

While the actualmass of copper of thebridging-member is or may less than that of a solid member, yet by reason of the laminated structure and the enhanced cooling effect, the current-carrying capacity of the member may be increasedi Due to the spaced relation of the bars comprisin the bridging member the superficial area presented to the Oll, when the ,switch is meved toward open position, is

considerably less than that which would be presented by a solid bar having the same overall dimensions and consequently the speed of the; menieer to open position and consequently the current-interrupting capacity of the switch may be increased.

in accordance with the value of current to be controlled by the switch.

Said bars 23 are carried by the supportthe stationary switch-members. Said bars 23 are also arranged to \be' independently self-aligning on said stationary switchmembers. For this'purpose each" of said bars has the two holes 23 formed therein on opposite sides of'its vertical medianline,"

andflpins 26 of smaller diameter than said holes are extended therethrough and through said arms 9A. of the supporting member, in

pins between the bars -to preserve proper [spacing therebetween. This arrangement is such that if, for instance, the top edge of a bar-extends above the edges of adjacent bars, said bar will rock about one or the other of said pins 26, when moved into con tact with the stationary switch-members, and the high end of the bar will be depressed and the low end of the bar raised until both ends of the bar are in contact with both stationary switch-members.

The arrangement of the bridging member also is such that the bars 23 may be turned edge for edge to present fresh contact faces whe the first used faces have become rough or bunned, and the effective life of the bridging member may thereby be doubled.

the arms 24 of the bridging-member supporting frame. The contact-member housingsare formed of strip material refiexed to form a rectangular structure having top and bottom wells aligned openings therein and side walls through which screws 30 are passed and threaded into the 'bars 29. Auxiliary contact members comprising the cylindrical rods 31 are slidably received in said openings and springs 32 encircfling them admit of their yielding'when in com tact with the stationary auxiliary contact members to admit further movement of the movable switch-members inswitch-closing direction. A flexible conductor 33 is ex tended between said contact members and connected thereto by the screws 34; and said conductor may also be secured to ihe bridging-member frame by the screws That feature of the invention wherein the junction between the movable and stationary switch-members is cooled may be also accomplished by providing the stationary contact'members, instead of the movable con- The number of bars employed will varyin this casefiis or maybe formed with alter-.

nate conducting-portions and oil channels arranged transversely of the iami'n'se'of brush Member. {The stationary cont ct- -member may comprise the block-4L2 ha slots in its lower face 'in which the bars are inserted and secured in any suitable 1 ner. The lower edges of said bars are adapted to be engaged by the brt l]--lllll1- bers and the spaces o a a said bars provide for about the bars whereby heat generated at the contact surface is dissipated.

it should be noted that, with this constructiom'the brushanember itself is cooled by reason of the spaced-relation otthe bars contacting therewith whereby to admit coolinp oil to the contact faces their-oil and b reason of the increased cooling effect, may carry an increased current for the same temperature rise.

The stationary auxiliary contact-menibers may comprise the llrshaped members disposed over the bars a l and secured removably to said blocks L2 by the screws l6.

The contact block 42 may be cut to form the alternate spaced conducting and heat dissipating bars-42 and oil channels is as illustrated in Figs. 11. and 12 if desired.

It is obvious that the structure herein disclosed may be otherwise modified without departing from the spirit of the invention.

1 claim:

I. An electric switch having a contactmember formed with a plurality of circulating passages for a cooling medium in its contact face. y

2. An electric switch having a contactmember formed "with a plurality oil relative ly deep and narrow circulating passages for cooling inits contact face through which oil is adapted to pass to cool the Contact member.

3. [in electric switch having a contactmcmbcr formed of a plurality cit-conducting components arranged to present a contactface for said'm'ember and circulating passages for a cooling medium'between them extended inwardly from the contact face by which to admit of the cooling of said con ducting components.

4-. A contactanember for an electric switch having a plurality of edge-wise arranged barsco-operatingto form a contact- 'tace for saidcontact-member and spacedapart to provide a plurality oi passages between them extended inwardly from the contact face to admit of the circulation of a cooling medium therethrough "for the cooling of said contact-member.

5.1m electric switch having two relatively movable contact-members each hav inc; co-operating contact-faces, one of said contact-members arranged circulation of cooling medium over portions of the contact face oil. said other contactanember when said members in contact. i

6. contact-member for an electric switch having a contact face and means to dissipate heat generated at its contact face comprising plurality oi? passages in said member extended below the contact :tace through which a cooling medium is adapted to circulate.

'1? An electric switch having a bruslrmemto admit of theeeaavi her and a cooperating contact member, 5:? contact-member hating a plurality oft lamina. arranged transversely of the laminae of the brush-members and spaced apart to provide passages through which a cooling;- medium is adapted to circulate.

8. Pin electric switch having a brusl'i-memher and a co-operating contact-member, said contact-member having a plurality of lai'ninre arranged transversely oi? the i. cc of the brush-members and spaced apart to provide passages through which a cooling medium is adapted to circulate and contact with said ln'ush-member and contact-1nemher to cool both.

9. fin electric switch having stationai switch-members includingbruslrmembers and a movable switch-member including a plurality of laminae arrangedtransversely the laminae of said brush-members and spaced apart to provide passages through which a fluid is adapted to circulate.

1.0. [in oil immersed electric switch having stationary switclrmembers and a bridging-member having a plurality oi? edgewisearranged conducting bars adapted to maize edgewise contact with said stationary switch-members and spaced apart to admit o'l? passage of oil therebetween.

11. An oil immersed electric switch hav- 'ing stationary switch-members and a movable switch member comprising a plurality of spaced bars having oil passages between them, whereby to increase the siecd o't switch-opening movement oi" said movable switchme1nber. A

12. An oil immersed switch having stationary switch-members and movable switch-member comprising a plurality of bridging bars spaced to provide oil passages therebctween extended in the direction of movement of said movable switch member.

.13. An electric switch comprising stationaiy switch-members and a movable switchmember including a plurality of spacedapart edgcwise arranged bars adapted to engage said stationary switch-members, and auxiliary contact members disposed beyond the'ends oi said bars;

fin electric switch comprising: station ary,switch-mcmbers and a movable switch member including; a supporting frame, a plurality of spaced apart, edgewise arranged bars extended on both sides beyond said frame, and means connecting said bars with said frame which admits of the aligning oi? the contact-faces of said bars in said frame.

fin electric switch having' a movable switch-member including a plurality of closely-spaced, ,edgewisc-arranged bars, a supporting; frame in which said bars are sc cured, bars having); two sets of aligned holes therethrough and pins of smaller diameter than said holes passed through. the two sets of holes and secured in said frame.

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whereby to admit of the rocking of said bars independently upon one or the other of said pins.

16. An electric switch including a fixed contact member having a contact face, a movable bridging-memberincluding a supedgewise-arranged bars removably secured reversibly in said frame.

' 18. An electric switch lncluding fixed contact member having a contact face, a movable bridging-member including a supporting-frame, a plurality of bars all are ranfged to engage the contact face of said fixed contactmember. and means pivotally supporting said bars in closely-spaced, edge- -wise order in said frame.

19. In an electric switch, a stationary.

switch-member including a laminated brush-member having, a shank portion and an angularly inclined toe-portion terminating in. a contact-face, and a brush-holder having side portions adapted to engage the sides of the laminae nd a shoulder adapted to engage the ends ofythe laminae in the shank-portion to conduct current therefrom.

20. In an electric switch, a stationary switch-member including a switch-stud,a laminated brush-member having a shankportion and an angularly inclined toe-portion terminating in a contact face, and a brush-holder having side portions adapted to engage the side of the laminae and a shoulder adapted to engage the ends of the laminae in the shank-portiontoconduct current therefrom and means removably to secure the holder to said switch-stud.

21. An electric switch comprising a fixed pair of brush members, and a movable bridging-member comprising a plurality of bars each adapted to engage said pair of including a supportingtact members,

brush members, and a switch rod carrying said bars.

22. An electric switch comprising a fixedpair of brush members, and; a movable bridging-member comprising aplurahty of bars each adapted to engage said pair of brush members, and a switch rod carrying said bars having, supporting mean's'for said bars by' which each bar is adapted for independent pivotal movement.

23. An electr'c switch comprising a fixed pair of inverted brush-members and a mov able bridgingmember comprising a plurality of-spaced bars adapted to be raised to engage and bridge said pair of brush members, and a switch rod carrying said bars.

-24. An electric switch having fixed conand a bridging-member adapted to bridge and connect said fixed contact members, said bridging member formed of a pluralityof bars adapted'to bridge and make independentedgewise contact with said contact members. I 2 5; An electric switch having the combination of a laminated fixed contact mem ber, alaminated movable contact member for said fixed contact member, and means to effect the engagement of said contact members with the laminations thereof angularly disposed to each other.

26. An electric switchhaving the combination of laminated fixed contact'members,

and a laminated movable bridging-member for said fixed contact members, th laminations' of said bridging member being angularly disposed to the laminations of said fixed contact members. y

27 In an electric switch, a stationary switch-member including a laminated brush: member having a shank portion and an angularly inclined toe-portion terminating in a contact-face and a. brush-holder having sid'e portions maintained in pressure-contact and electrical engagementwith the sides of the laminae. i

. In testimony whereof, I have signed my name to this specification.

GEORGE BURNHAM. 

